Problems relating to the shelf stability of enzyme-containing surfactant preparations, for example of washing, cleaning, or disinfecting agents, are known from the existing art. This problem is especially acute with liquid enzyme-containing surfactant preparations, for example liquid washing or cleaning agents. After only a short time they lose a significant degree of enzymatic, in particular hydrolytic, and especially proteolytic activity. The surfactant preparation, for example the washing, cleaning, or disinfecting agent, then no longer exhibits optimum cleaning performance. One objective in the context of the development of enzyme-containing surfactant preparations is therefore to stabilize the contained enzymes and to protect them from denaturing and/or cleavage and/or degradation, in particular during storage and/or during utilization of the surfactant preparation. Hydrolytic enzymes in particular, and especially proteases, are of interest in this regard.
Boric acid and boric acid derivatives occupy a prominent position among the enzyme stabilizers that are effective in surfactant preparations even at a comparatively low concentration. International patent application WO 96/21716 A1, for example, discloses that boric acid derivatives and boronic acid derivatives acting as protease inhibitors are suitable for stabilizing enzymes in liquid preparations, among them washing and cleaning agents. A selection of boronic acid derivatives as stabilizers is disclosed, for example, in international patent application WO 96/41859 A1. WO 92/19707 A1 and EP 478050 A1 present meta- and/or para-substituted phenylboronic acids as enzyme stabilizers. Complexes of boric acids and boric acid derivatives with aromatic compounds as enzyme stabilizers in liquid detergent compositions are disclosed in EP 511456 A.
Boric acids and boric acid derivatives have the disadvantage, however, that they form undesired secondary products with other ingredients of a surfactant preparation, in particular washing-, cleaning-, or disinfecting-agent ingredients, so that they are no longer available in the relevant agents for the desired cleaning purpose, or in fact remain behind, for example on the washed item, as a contaminant. In addition, boric acids and borates are increasingly being regarded as disadvantageous in environmental terms.
The underlying object of the present invention is to make available a liquid surfactant preparation having stabilized hydrolytic enzymes. The surfactant preparation should preferably contain fewer boron-containing compounds as enzyme stabilizers.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.